Don't copy hidden files/directories during `setup.py install`

This is useful if a copy of Mercurial is stored in a Subversion repository
so that the .svn directories don't get copied.

setup.py

@@ -248,6 +248,8 b" if sys.platform == 'linux2' and os.uname"
 datafiles = []
 for root in ('templates', 'i18n'):
     for dir, dirs, files in os.walk(root):
+        dirs[:] = [x for x in dirs if not x.startswith('.')]
+        files = [x for x in files if not x.startswith('.')]
         datafiles.append((os.path.join('mercurial', dir),
                           [os.path.join(dir, file_) for file_ in files]))